1. Field of the Invention
The invention concerns email processing, and in particular, ensuring email messages are sent to the correct address domain.
2. Description of the Related Art
As the growth of email continues, the potential for messages to be addressed incorrectly likewise increases. Email address take the well known format “user@domain”, where “user” is a unique user identifier at a given “domain name” address. A domain name is the unique name of a computer on the Internet that distinguishes it from the other systems on the network. Every website, email account, etc, on the Internet is hosted on at least one computer (server) a having unique IP address. Because it is difficult to remember numbers, an IP address can be associated with a fully qualified host name (a domain name), such as “www.foo.com”. Domain names also provide a persistent address for some service when it is necessary to move to a different server, which would have a different IP address.
On the Internet, the destination domain's configuration determines where to deliver a message. Generally the message is delivered first determining what host the message should be sent to and then delivering it directly to that host. The sending server will first look for a Mail Exchanger (MX) record for its domain in a DNS database. MX records are always assigned a preference. If several mail exchangers exist for one host, the mail transport agent will try to transfer the message to the exchanger with the lowest preference value, and only if this fails will it try a host with a higher value. If there is no MX record for a domain, or no MX records left that are suitable, the mail transport agent is permitted to see if the domain has an IP address associated with it (an address or “a-” record) and attempt delivery directly to that host.
Currently, if a sending email server can find either an MX record or an address record, but cannot deliver the mail, the sending server's queue is impacted as well as the user who send the original mail. This problem has become more acute due to the large number of domain names registered every year which have address records, but which are not used for any real purpose. In addition, mistyped email domains are particularly problematic for email service providers, such as Hotmail and Yahoo mail, where users' can routinely misspell domain names.
Errors in an email address can result from an error in the user address name or in the domain name. When a sender initiates transmission of an email message, the sender's messaging server attempts to make delivery using standard protocols. If an error in the addressee's name is present, but the domain is correct, the sender's messing server should be able to make contact with the addressee's domain mail server. The addressee's server will indicate that no such user is present at the domain and an error will be returned to the sender, generally within a short period of time.
However, if the error is in the domain name portion of the intended recipient's address, the error may not be known to the user for some time. Generally, if a mail system cannot communicate with a domain to deliver mail to it, the mail server will queue the outbound mail for some period of time (on the order of days) before indicating a mail delivery failure. If a mail is still undeliverable after a configured elapsed time interval, then a Non Delivery Report is sent. Once a mail is accepted by the user's own mail server, many users will assume it has been delivered, even thought it actually remains in the mail server's queue. It is not until the mail delivery is attempted that the user might get an NDR, and in some cases, if the domain name was mistyped or if the domain is not configured to accept mail, then it may be multiple days (waiting for time out parameters) before an NDR is sent.